The present invention relates to a fluid control system, and in particular to a modular, valve-operated fluid control system. In many industrial applications, it is necessary to provide a large number of individually-controllable pneumatic or hydraulic fluid lines. In practice, this requires at least one electronically-operated solenoid valve to be provided for each fluid line. Rather than provide each valve with its own power and control leads, which would be impractical, it is known to connect all of the solenoid valves to a single power supply, provide a common data bus on which control signals are transmitted, and provide each valve with a controller for interpreting the control signals and operating the valve as required. EP-A-0299655 discloses one example of such a fluid control system.
Such fluid control systems are generally complex, requiring elaborate control protocols and data decoders within the valve controllers to derive the specific instructions for each valve. In addition, it is usually necessary to provide each valve with a unique pre-set address or means for setting a unique address, such as a position encoder, to enable instructions to be transmitted to particular valves. This requirement introduces further complexity and leads to problems if addresses become non-unique. Furthermore, although some of the fluid control systems of the above-described kind may be described as xe2x80x9cmodularxe2x80x9d, for example, the system disclosed in U.S. Pat. No. 5,522,431 in which a common fluid manifold is provided by combining a plurality of separate manifold modules, those systems do not allow simple system construction or system expansion. Those systems, which are sold through a distributor, are pre-configured by the manufacturer according to a particular specification. As such, those systems do not allow for alteration by adding or removing valves without the need for substantial re-adjustment or system re-wiring/re-programming.
It is thus an aim of the present invention to provide a modular fluid control system which can be easily configured, typically by distributors, by simply fitting together the required components in the desired configuration from a small range of different standard modules, and which, when powered up, is fully configured and ready for operation without the need for additional complicated wiring.
Accordingly, the present invention provides a modular fluid control system, comprising: a control module for receiving parallel electronic control signals as a plurality of data streams, the control module including a control unit configured to convert the data streams of the parallel electronic control signals to serial electronic control signals, each including a plurality of data pulses as control instruction signals, and an electrical connector; a plurality of valve modules, each valve module including at least one valve operable to control the flow of pressurized fluid; and a plurality of manifold modules connectable in series to the control module and connected to respective ones of the valve modules, each manifold module including a fluid supply conduit to provide a common manifold for receiving pressurized fluid, first and second electrical connectors for connection with ones of the connectors of adjacent manifold modules and the connector of the control module to provide an electrical bus for transmission of the serial control signals and power supply, and a control unit configured to decode one or more of the first-received data pulses of the serial control signals, control the respective valve module accordingly, and pass any remaining data pulses as a modified serial control signal from which the decoded data pulses have been one of removed or blocked to the control unit of any downstream manifold module.
Preferably, the manifold modules are non-addressed.
In one embodiment the control system comprises a single group of series-connected manifold modules.
In another embodiment the control system comprises a plurality of interconnected groups of series-connected manifold modules, and further comprises intermediate connection modules connected to the intermediate ends of the groups of manifold modules.
Preferably, the control system further comprises an end connection module connected to the end of the series-connected manifold modules.
Preferably, one of the control module or the end connection module includes a port for connection to a supply of pressurised fluid.
Preferably, the serial control signals are pulse width modulated signals.
More preferably, data pulses having different pulse widths designate different control states.
Yet more preferably, the pulse widths are the active pulse widths.
Preferably, the control unit of each manifold module is further configured to operate the respective valve module only on consecutively receiving the one or more data pulses having the same pulse widths a predetermined number of times.
More preferably, the control unit of each manifold module is configured to operate the respective valve module only on consecutively receiving the one or more data pulses having the same pulse widths at least three times.
Preferably, the valve modules include one of mono-stable or bi-stable valves.
More preferably, the control unit of any manifold module connected to a valve module including a mono-stable valve is configured to decode the first-received data pulse of each of the received serial control signals.
More preferably, the control unit of any manifold module connected to a valve module including a bi-stable valve is configured to decode the first- and second-received data pulses of each of the received serial control signals.
Preferably, the control unit of the control module is further configured to terminate each of the serial control signals generated thereby with a termination signal to denote the end of each of the serial control signals.
Preferably, the control unit of each manifold module is further configured to transmit return data signals to the control module.
More preferably, the control unit of each manifold module is configured to transmit return data signals to the control module on receipt of the termination signal.
More preferably, the control unit of the control module is further configured to convert the return data signals to parallel return data signals.
Preferably, the manifold modules each comprise a body which includes a passage, and a printed circuit board housed in the passage which includes the connectors and the control unit, with the passages together defining a common passage in which the printed circuit boards are connected.
Preferably, the main body of each manifold module is formed as an integral component.
The fluid control system of the present invention, in being simple and requiring no re-wiring of the component parts, allows for configuration by non-skilled technicians, thus allowing for configuration by parties other than the manufacturer, such as a distributor.
In its preferred embodiments the fluid control system of the present invention automatically provides a xe2x80x9cvirtual connectionxe2x80x9d between valve modules at any given location with reference to the respective pin or pins of the external connector. In the event that alteration of the configuration of the system is required, the system may be quickly disassembled, manifold modules and associated valve modules added, removed or re-arranged and then re-assembled. The new positions of the re-arranged valve modules will automatically correspond to the correct pin or pins of the external connector without the need to re-wire the system.